Monday, 21 May 2012

Modulation, AM or FM?

Modulation, AM or FM? Many (many!) years ago
, I was a telephone engineer in the UK, and went to college to learn my craft.
One afternoon we learnt about radio and what was meant by AM and FM - Amplitude
Modulation and Frequency Modulation. What I don't remember is the why and how
of AM and FM, and to be honest I now leave it to the radio experts to ponder
such things!

These days, modulation
is to do with music for me. A lot of jazz is based on the use of 'standards'
that is songs written by composers originally for the theatre, tin pan alley or
the hit parade and then taken by us jazzers to make our own by improvising
around these wonderful pieces.

Take 'How about you'
for example, a great standard to jazz around. The lyrics of the first bit go:

I like New York in
June,

how about you?

I like a Gershwin
tune,

how about you?

I love a fireside

when a storm is due.
I like potato chips,

moonlight and motor
trips,

how about you?

Let's say we're
playing the piece in the key of F (one flat) a favourite for this piece.

Every thing goes
alright, with straight forward chords until we come to "I like potato
chips, moonlight and motor trips, how about you?"

On the face of it we
see some strange chords for the key of F, until realise, that bit is in fact in
a different key, the key of A (three sharps) in this case. What has happened is to the piece has
modulated into a new key, for a bit. As the piece goes on it goes back to the key of F and
all is well again!

What the jazzer has to
do in fact, is to recognise these temporary key changes, or modulations,
because the jazzer will use different scales to solo (extemporise) around that
modulated bit. The important thing to remember is that modulation is only a temporary
change of key within the piece - and that's because the composer has written it in, and not a complete key
change. If you changed the key to of the whole piece to G (one sharp) for example,the
modulation as above would now be in the key of B (5 sharps)!

Modulations within
pieces make them sound really cool, as I sometimes think that pieces that don't
modulate seem to go nowhere! The same of course is true in classical music,
where modulations are all over the place!

So to get to grips
with modulation and how it affects you as a jazzer, go on a Jazz Workshop and
all will be revealed